This invention relates to a wire supply method and apparatus particularly for stator winding machines. The method and apparatus of this invention are especially adapted for use in the high speed winding of 2-pole stators but the invention is not necessarily so limited.
Procedures for winding coils on 2-pole stators are described in U.S. Pat. No. Re 25,281 granted to H. W. Moore on Nov. 6, 1962 and U.S. Pat. No. 3,251,559 granted to H. W. Moore on May 17, 1966. A typical 2-pole stator winding machine includes a winding head or shuttle having a pair of wire guide nozzles or needles. Two wires, one for each of the needles, are coursed from a pair of wire supply spools through the shuttle and extended out of the needles. The shuttle is reciprocated to repeatedly pass in opposite directions through the stator core. At each end of its reciprocatory travel the shuttle is oscillated about its axis, the direction of oscillation being opposite at opposite ends of the stator. Accordingly, the coil end turns are formed during the oscillatory motions and the coil sides are formed during the reciprocatory motions of the shuttle.
At the beginning of the winding of coils on a stator, the forward ends of the wires are clamped or tied down and the wires exiting from the supply spools are coursed through wire tensioning and dereeling devices so that, ideally, the wires are under tension throughout the winding operation and the coil turns will closely follow the contours of the winding forms. A typical prior tensioning and dereeling device is shown in U.S. Pat. No. 2,643,075 granted to K. A. Moore on June 23, 1953.
A powered wire takeup device has also been used which operates in synchronism with the winding shuttle, such a takeup device being disclosed in the above mentioned U.S. Pat. No. 3,251,559. In general, the wire takeup device shown in the '559 patent draws wire when the winding head is not drawing wire and then releases the wire when the winding head is drawing wire so that there is a more uniform demand for wire from the dereeler. The apparatus shown in the '559 patent has been successfully used on stator winding machines having shuttle spindles which operate in the range of 800 or 900 complete strokes per minute.
It has been discovered that a combination of a dereeling device such as shown in the above mentioned K. A. Moore U.S. Pat. No. 2,643,075 and the powered wire takeup device shown in the H. W. Moore U.S. Pat. No. 3,251,559 do not adequately control the wire tension for stator winding machines having shuttle speeds operating in the range of 1000 or more complete strokes per minute. As a result, the wires exiting from the winding head of such machines may tend to balloon outwardly instead of closely following the guide surfaces which are provided for the wire. The wound coils have loosely formed turns and, especially with fine wire, breakage may occur.
More elaborate tensioning and dereeling devices have been developed especially for high speed winders operating in excess of 800 or 900 complete strokes per minute, one such device being shown in U.S. Pat. No. 4,062,502, granted to K. E. Peck, Jr., on Dec. 13, 1977. The apparatus of the '502 patent may be used with winding machines operating at shuttle speeds as high as 1200 complete strokes per minute but in some cases, particularly with fine wire, such apparatus is not successful in preventing wire breakage or loosely wound coils at that speed.
To date there has been no fully satisfactory device known to applicant developed for use with a high speed stator winder operating in the range of approximately 1200 complete strokes per minute or higher without the formation of loosely wound coils or without occasional wire breakage. Wire breakage is believed to be caused by abrupt reversals in the directions of shuttle movement and also because the momentum of the wires at the end of the reciprocating strokes causes them to balloon outwardly from the shuttle needles where they may become snagged on parts of the stator being wound or on nearby parts of the machine. It has been suggested to locate shields between the winding needles and parts on which the wires tend to snag. However, so far as known, no fully satisfactory shield has been developed. U.S. Pat. No. 4,199,115, issued to Richard N. Lachey on April 22, 1980, discloses a wire control device that may reduce the effects of wire ballooning in certain cases but does not fully overcome the problems of loosely wound coils and wire breakage. Recently, a demand has arisen for stator winding machines operating in the range of approximately 1800 or more complete strokes per minute and the known devices for supplying wire to the winding machine are inadequate to provide a reliable source of wire under the uniform tension needed to prevent loose coils and wire breakage.